PROJECT SUMMARY/ABSTRACT Functional Neurological Disorder (FND/ Conversion Disorder) is a highly prevalent and disabling neuropsychiatric condition. Motor FND symptoms include Nonepileptic Seizures, Functional Movement Disorders and Functional Weakness. Clinical research across these motor FND subtypes, including research studies from the candidate's laboratory, suggest that these populations share many clinical and phenotypic similarities that warrant increased research integration (Perez et al. Cogn Behav Neurol 2016; Matin & Perez et al. J Neuropsychiatry Clin Neurosci 2017). Furthermore, despite the prevalence of motor FND, little is known about the underlying neuropathophysiology of this condition, which is a prerequisite for the development of biologically informed prognostic and treatment response biomarkers. Across 3 published neurobiologically focused articles, the candidate proposed a framework through which to conceptualize motor FND (Perez et al. J Neuropsychiatry Clin Neurosci 2012, 2015, Clin EEG Neurosci 2015). It is suggested that motor FND develops in the context of structural and functional alterations in neurocircuits mediating emotion awareness/expression, bodily awareness, viscerosomatic processing and behavioral regulation. A particular focus of this grant application is the specific hypothesis that FND symptoms relate to structural and functional alterations within the salience network, which includes the anterior insula, anterior cingulate cortex, dorsal amygdala and periaqueductal gray. The overall goal of this proposal is to comprehensively investigate structural and functional MRI biomarkers of symptom severity, adverse life event burden (a FND risk factor) and prognosis across motor FND. Across aims 1-3 of this proposal, multimodal structural and functional magnetic resonance imaging (MRI) techniques (including voxel-based morphometry, cortical thickness, resting-state functional connectivity and diffusion tensor imaging tractography) are used to systemically probe brain-symptom severity, brain-trauma burden and brain-prognosis relationships. Novel aspects of this proposal include the study of the full spectrum of motor FND, consistent with a trans-diagnostic approach and Dr. Perez's training in the full complement of structural and resting state functional MRI techniques. This project leverages the candidate's past fMRI experience probing brain-symptom relationships in other neuropsychiatric disorders (Perez et al. Psychiatry Res 2015; Psychiatry Clin Neurosci 2016), as well as Dr. Perez's recently published MRI study probing gray matter volume associations with self-report measures of symptom severity and childhood abuse burden in patients with motor FND (Perez et al. J Neurol Neurosurg Psychiatry 2017). Pilot data for all 3 aims is presented in this proposal. These studies in motor FND will identify trans-diagnostic neural biomarkers linked to symptom severity, adverse life events and prognosis. The results of this project will catalyze future comprehensive prognostic and treatment research including the potential future study of targeted neuromodulation and treatment response biomarkers based on baseline neuroimaging profiles.